Monthly Notifiable Disease Surveillance Report - Jul 2018

Saturday 23rd February 2019

Key notifiable disease trends

Enteric Diseases: Enteric infections are the most common notifiable diseases, and several are increasing in incidence. This increase is partly due to changes in laboratory testing practices with a shift from culture methods to multiplex PCR, which tests for several diseases at the same time. This means more diseases are likely to be detected and in a timelier manner. For further information, see the 2016 Annual Notifiable Disease Report Commentary.

Dengue fever: There were 13 cases (9 confirmed, 1 probable and 3 under investigation) of dengue fever notified in July 2018, compared with three cases in July 2017. Travel history was recorded for 12 (92.3%) cases and the other has since been made 'Not a case'. Countries visited were Thailand (5 cases), Fiji and Indonesia (2 cases each), Philippines, Tonga and Vietnam (1 case each). The serotype was recorded for six of the confirmed cases: DENV-2 (4 cases), DENV-3 and DENV-4 (1 case each).

Meningococcal Disease: There have been 54 cases (50 confirmed, 2 probable and 2 under investigation) of meningococcal disease notified from January to July 2018, of which 13 were identified as group W, compared with three group W cases for the same period in 2017. One death due to group W was reported in July 2018. A marked increase in group W cases has been reported in several countries overseas. More information can be found in the March 2018 NZ Public Health Surveillance Report and in this immunisation update.Two cases of group B meningococcal disease associated with the University of Otago halls of residence were reported by Public Health South in July. Both were confirmed with the same strain as two cases reported earlier this year at one of the halls of residence. All staff and students at this hall of residence, along with close contacts of the second case reported in July, have been treated with eradication antibiotics.

Mumps: There were 20 cases (6 confirmed, 9 probable and 5 under investigation) of mumps notified in July 2018, compared with 76 cases in July 2017. The majority of confirmed and probable cases were from the Auckland region (10 cases). Monthly mumps notifications have decreased since October 2017 when 277 confirmed and probable cases were reported.

Pertussis: There were 171 cases (83 confirmed, 68 probable, 10 suspect and 10 under investigation) of pertussis notified in July 2018, compared with 95 cases in July 2017. While pertussis cases have been decreasing since the peak in January 2018, this is not unusual and cases may increase again, as in the 2012 outbreak. A national outbreak is ongoing. For more information see the latest Pertussis Report.

Typhoid fever: Seven cases of typhoid fever were notified in July 2018, compared with no cases in July 2017. Five were confirmed as Salmonella Typhi infections by ESR while one was confirmed to be Salmonella enteritidis (i.e. not typhoid). One case has no laboratory confirmation and is under investigation. Risk factors were recorded for two of the five confirmed typhoid cases, with one reporting recent overseas travel to India and the other having a family member who was found to be an asymptomatic carrier.

OUTBREAKS

Norovirus: Sixteen norovirus outbreaks (12 finalised and 4 interim) were reported in July, involving 182 cases. Most of the outbreaks were in Canterbury DHB (12 outbreaks). The exposure setting was recorded for 12 outbreaks (75.0%): acute care hospital (6 outbreaks), long term care facility (5) and other institution (1).

Clostridium perfringens: An outbreak of Clostridium perfringens involving 21 cases was reported from Community and Public Health in Christchurch in July. The outbreak was associated with consumption of a pork rice dish at a church fund-raising event, with all of the symptomatic people having consumed it. All recovered within 48 hours and none required a doctor's visit. C. perfringens was detected in a faecal specimen and also in the leftover food – although not at a level considered to cause serious illness. Contributing factors were inadequate reheating of previously cooked food and improper storage.